#!/usr/bin/env python3
#
# Copyright (C) 2020-2024 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import os
import sys
import grp
import re
import json
import typing
import logging
import signal
import importlib.util
import zmq
from contextlib import contextmanager

from vyos.defaults import directories
from vyos.utils.boot import boot_configuration_complete
from vyos.configsource import ConfigSourceString
from vyos.configsource import ConfigSourceError
from vyos.configdep import call_dependents
from vyos.config import Config
from vyos import ConfigError

CFG_GROUP = 'vyattacfg'

script_stdout_log = '/tmp/vyos-configd-script-stdout'

debug = True

logger = logging.getLogger(__name__)
logs_handler = logging.StreamHandler()
logger.addHandler(logs_handler)

if debug:
    logger.setLevel(logging.DEBUG)
else:
    logger.setLevel(logging.INFO)

SOCKET_PATH = "ipc:///run/vyos-configd.sock"

# Response error codes
R_SUCCESS = 1
R_ERROR_COMMIT = 2
R_ERROR_DAEMON = 4
R_PASS = 8

vyos_conf_scripts_dir = directories['conf_mode']
configd_include_file = os.path.join(directories['data'], 'configd-include.json')
configd_env_set_file = os.path.join(directories['data'], 'vyos-configd-env-set')
configd_env_unset_file = os.path.join(directories['data'], 'vyos-configd-env-unset')
# sourced on entering config session
configd_env_file = '/etc/default/vyos-configd-env'

session_out = None
session_mode = None

def key_name_from_file_name(f):
    return os.path.splitext(f)[0]

def module_name_from_key(k):
    return k.replace('-', '_')

def path_from_file_name(f):
    return os.path.join(vyos_conf_scripts_dir, f)

# opt-in to be run by daemon
with open(configd_include_file) as f:
    try:
        include = json.load(f)
    except OSError as e:
        logger.critical(f"configd include file error: {e}")
        sys.exit(1)
    except json.JSONDecodeError as e:
        logger.critical(f"JSON load error: {e}")
        sys.exit(1)

# import conf_mode scripts
(_, _, filenames) = next(iter(os.walk(vyos_conf_scripts_dir)))
filenames.sort()

load_filenames = [f for f in filenames if f in include]
imports = [key_name_from_file_name(f) for f in load_filenames]
module_names = [module_name_from_key(k) for k in imports]
paths = [path_from_file_name(f) for f in load_filenames]
to_load = list(zip(module_names, paths))

modules = []

for x in to_load:
    spec = importlib.util.spec_from_file_location(x[0], x[1])
    module = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(module)
    modules.append(module)

conf_mode_scripts = dict(zip(imports, modules))

exclude_set = {key_name_from_file_name(f) for f in filenames if f not in include}
include_set = {key_name_from_file_name(f) for f in filenames if f in include}

@contextmanager
def stdout_redirected(filename, mode):
    saved_stdout_fd = None
    destination_file = None
    try:
        sys.stdout.flush()
        saved_stdout_fd = os.dup(sys.stdout.fileno())
        destination_file = open(filename, mode)
        os.dup2(destination_file.fileno(), sys.stdout.fileno())
        yield
    finally:
        if saved_stdout_fd is not None:
            os.dup2(saved_stdout_fd, sys.stdout.fileno())
            os.close(saved_stdout_fd)
        if destination_file is not None:
            destination_file.close()

def explicit_print(path, mode, msg):
    try:
        with open(path, mode) as f:
            f.write(f"\n{msg}\n\n")
    except OSError:
        logger.critical("error explicit_print")

def run_script(script, config, args) -> int:
    script.argv = args
    config.set_level([])
    try:
        c = script.get_config(config)
        script.verify(c)
        script.generate(c)
        script.apply(c)
    except ConfigError as e:
        logger.critical(e)
        explicit_print(session_out, session_mode, str(e))
        return R_ERROR_COMMIT
    except Exception as e:
        logger.critical(e)
        return R_ERROR_DAEMON

    return R_SUCCESS

def initialization(socket):
    global session_out
    global session_mode
    # Reset config strings:
    active_string = ''
    session_string = ''
    # check first for resent init msg, in case of client timeout
    while True:
        msg = socket.recv().decode("utf-8", "ignore")
        try:
            message = json.loads(msg)
            if message["type"] == "init":
                resp = "init"
                socket.send(resp.encode())
        except:
            break

    # zmq synchronous for ipc from single client:
    active_string = msg
    resp = "active"
    socket.send(resp.encode())
    session_string = socket.recv().decode("utf-8", "ignore")
    resp = "session"
    socket.send(resp.encode())
    pid_string = socket.recv().decode("utf-8", "ignore")
    resp = "pid"
    socket.send(resp.encode())
    sudo_user_string = socket.recv().decode("utf-8", "ignore")
    resp = "sudo_user"
    socket.send(resp.encode())

    logger.debug(f"config session pid is {pid_string}")
    logger.debug(f"config session sudo_user is {sudo_user_string}")

    try:
        session_out = os.readlink(f"/proc/{pid_string}/fd/1")
        session_mode = 'w'
    except FileNotFoundError:
        session_out = None

    # if not a 'live' session, for example on boot, write to file
    if not session_out or not boot_configuration_complete():
        session_out = script_stdout_log
        session_mode = 'a'

    os.environ['SUDO_USER'] = sudo_user_string

    try:
        configsource = ConfigSourceString(running_config_text=active_string,
                                          session_config_text=session_string)
    except ConfigSourceError as e:
        logger.debug(e)
        return None

    config = Config(config_source=configsource)
    dependent_func: dict[str, list[typing.Callable]] = {}
    setattr(config, 'dependent_func', dependent_func)

    return config

def process_node_data(config, data, last: bool = False) -> int:
    if not config:
        logger.critical(f"Empty config")
        return R_ERROR_DAEMON

    script_name = None
    args = []

    res = re.match(r'^(VYOS_TAGNODE_VALUE=[^/]+)?.*\/([^/]+).py(.*)', data)
    if res.group(1):
        env = res.group(1).split('=')
        os.environ[env[0]] = env[1]
    if res.group(2):
        script_name = res.group(2)
    if not script_name:
        logger.critical(f"Missing script_name")
        return R_ERROR_DAEMON
    if res.group(3):
        args = res.group(3).split()
    args.insert(0, f'{script_name}.py')

    if script_name not in include_set:
        # call dependents now if last element of prio queue is run
        # independent of configd
        if last:
            call_dependents(dependent_func=config.dependent_func)
        return R_PASS

    with stdout_redirected(session_out, session_mode):
        result = run_script(conf_mode_scripts[script_name], config, args)

    if last and result == R_SUCCESS:
        call_dependents(dependent_func=config.dependent_func)

    return result

def remove_if_file(f: str):
    try:
        os.remove(f)
    except FileNotFoundError:
        pass
    except OSError:
        raise

def shutdown():
    remove_if_file(configd_env_file)
    os.symlink(configd_env_unset_file, configd_env_file)
    sys.exit(0)

if __name__ == '__main__':
    context = zmq.Context()
    socket = context.socket(zmq.REP)

    # Set the right permissions on the socket, then change it back
    o_mask = os.umask(0)
    socket.bind(SOCKET_PATH)
    os.umask(o_mask)

    cfg_group = grp.getgrnam(CFG_GROUP)
    os.setgid(cfg_group.gr_gid)

    def sig_handler(signum, frame):
        shutdown()

    signal.signal(signal.SIGTERM, sig_handler)
    signal.signal(signal.SIGINT, sig_handler)

    # Define the vyshim environment variable
    remove_if_file(configd_env_file)
    os.symlink(configd_env_set_file, configd_env_file)

    config = None

    while True:
        #  Wait for next request from client
        msg = socket.recv().decode()
        logger.debug(f"Received message: {msg}")
        message = json.loads(msg)

        if message["type"] == "init":
            resp = "init"
            socket.send(resp.encode())
            config = initialization(socket)
        elif message["type"] == "node":
            if message["last"]:
                logger.debug(f'final element of priority queue')
            res = process_node_data(config, message["data"], message["last"])
            response = res.to_bytes(1, byteorder=sys.byteorder)
            logger.debug(f"Sending response {res}")
            socket.send(response)
        else:
            logger.critical(f"Unexpected message: {message}")
